Denture Liner, Denture Liner Kit And Method For Making A Denture Liner

ABSTRACT

A denture liner for fitting a denture to gums in a mouth, comprising a self-supporting and shape-retaining layer that comprises a volume of a hydrophobic polymer component that inhibits the liner from absorbing moisture and a volume of a hydrophilic polymer component that hydrates a surface of the liner when exposed to moisture.

This application is a continuation-in-part of U.S. patent application Ser. No. 10/987,833, filed Nov. 12, 2004, which application is currently pending and which application is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to dental compositions based on blends of particular polymer, plasticizer, and adhesive constituents, and to the process of making such compositions. The compositions are useful in prosthodontics, including formulating denture liners which have a glass transition temperature lower than the lower of an ambient temperature at which the liner is applied and a temperature inside the oral cavity. The most preferred embodiments are phthalate free. The invention further relates to denture liner kits.

BACKGROUND OF THE INVENTION

When a denture is worn for a long period of time, the fit between the denture and the alveolar ridge worsens. The shape of the gums changes with time as the gums recede. Since the denture is made from a hard material, it is incapable of adjusting to the change in shape of the gums. Thus, gaps begin to form between the denture and the gums. This can lead not only to the loosening of the denture, but also to an ulcer and/or inflammation due to uneven pressure exerted by the denture.

To alleviate these problems, it is necessary to provide a liner between the denture and the gum, which can both fill in the gaps that form between the denture and the gum and prevent damage to the gum. This liner may be flexible and plastically deformable, and may be capable of being used for a period of, for example, one week to a few weeks.

Numerous denture liners have been proposed to provide both comfort and better fit for the denture. Many of such liners achieve this goal by being soft, allowing them to conform to the shape of both the gums and the denture.

Conventionally, a soft denture liner is made of a synthetic resin in the form of powder, paste or a soft plate. Each time a user needs to apply a denture to the gum, the user takes the required amount of a denture base stabilizing material from a receptacle in the case of a powder or paste, or shapes it in an appropriate size and configuration in the case of a soft sheet. Conventional soft denture liners include various polymers, such as polyethylene, polypropylene, polybutene, polyvinyl chloride, ethylene-vinylacetate copolymer, nylon, polyvinyl flouride, Teflon, polyacrylonitrile and polyvinyl alcohol. Conventional soft denture liners in the form of pastes and powders are highly hydrophilic and readily absorb moisture forming an adhesive gel. These pastes and powders can be problematic in that they do not remain on the denture once the denture is inserted into the oral cavity. Once inserted, force is applied to the denture in order to ensure a snug fit of the denture to the gums. The force of application will cause the gums to displace the paste or gel that is formed and these adhesives will ooze or squirt out the side of the denture. Thus, the adhesive will not be retained on the denture reducing the ability of the denture to be secured to the gums. Pastes and powders can be difficult to use because they require the denture wearer to ensure that the paste or powder is uniformly applied. Pastes and powders are also deficient in that once the denture is removed these pastes and formed gels must be cleaned off of the denture.

Several soft denture liners have been disclosed, which are based on plasticized polyethyl methacrylate (PEMA). One such denture liner is disclosed in U.S. Pat. No. 5,061,182 to Kubo et al. (herein incorporated by reference). The patent discloses a denture base stabilizing sheet having a trapezoidal configuration, which is manufactured using a specific composition of PEMA, butyl phthalyl butyl glycolate (BPBG), and triacetin.

Soft liners mainly consisting of polymers of higher methacrylates, e.g., polyethylmethacrylate, a solvent, e.g., ethyl alcohol, and a plasticizer, e.g. butylphthalyl butylglycolate have also been described. These and others are disclosed in Graham et al, J., Prosthetic Dentistry, Volume 2, No. 4, pp. 422-8 (1989). The solvent and plasticizer are mixed with the polymer immediately prior to use, and the mixture is then applied to the surface of the denture. Swelling of the polymer by the solvent, and diffusion of the plasticizer into the polymer matrix cause the polymer to become soft and resilient.

U.S. Pat. No. 5,075,107 to Katakura (herein incorporated by reference) discloses a denture liner, which specifically excludes ethyl alcohol. This liner comprises a powdery component consisting of (a) either one of a copolymer of butyl methacrylate with ethyl methacrylate and a mixture of poly butyl methacrylate (PBMA) with PEMA and (b) a liquid component consisting of at least one of BPBG without ethanol, dibutyl phthalate (DBP), benzyl butyl phthalate, benzyl benzoate, ethyl benzoate, butyl benzoate and amyl benzoate, with the powdery and liquid components being mixed or kneaded together for use.

Another denture liner based on plasticized PEMA is disclosed in U.S. Pat. No. 5,436,283 to Okada et al. (herein incorporated by reference). The patent discloses a denture base lining material comprising a phthalic ester-based plasticizer containing ethyl alcohol and a powder component consisting of PEMA with or without a specific acrylate copolymer.

U.S. Pat. No. 5,513,988 relates to a known elastomeric methyl methacrylate-free soft material used as a denture reline material. The material includes powder and liquid components mixed together and cured, then used in denture applications. Where the invention involves lining over a void in an acrylic denture, the resultant mixture is applied over the underlying surface of the acrylic over the void to chemically and mechanically bond the mixture in a seamless bond to the underlying surface of acrylic. A known sealer component is then applied over the liner to create a non-absorbent exterior surface seal and glaze.

While the above conventional denture liners can provide some of the much needed relief for denture wearers, these liners have a number of problems. Conventional denture liners include polymeric materials, such as PEMA, which are chemically similar to the materials from which dentures are formed. These types of material allow the liner to be flexible and to be able to adjust to the changing shape of the gums. However, the liners tend to chemically bond to the denture, especially when the plasticizers are liberated over time. Thus, the liners become extremely difficult to separate from the denture. This is especially true with the materials discussed in U.S. Pat. No. 5,513,988 which promote chemical and mechanical bonding between the liner and the denture. Conversely, the instant invention promotes formation of adhesive bonding by providing a denture lining material which has a low glass transition temperature and can be characterized as resilient, as well as sticky or tacky.

Also, conventional denture liners do not have mucoadhesive properties. Therefore, they rely on either physically fitting the denture to the gum or on an additional adhesive. Such an approach, however, is deficient in that it leads to an inadequate hold or requires addition of a separate layer or layers of adhesives, which may interfere with the function of the liner and result in discomfort for the user.

The above-mentioned U.S. Pat. No. 5,436,283 attempts to solve the problem associated with separating the liner from the denture by including liquid paraffin and/or squalane in the composition of the liner. While such a modification helps to peel the liner from the denture, liquid paraffin and squalane also decrease the adhesion of the liner to the gum, which can lead to denture slippage.

Also problematic is the inclusion of phthalates in the plasticizer component of state-of-the art denture liners. Various advocacy groups are complaining that animal studies suggest that phthalates cause damage to an animal's internal organs such as kidneys, liver, lungs, and the reproductive system, including the testes. Since dentures and denture liners are worn in the mouth of the user where ingestion of phthalates may occur, it is desirable to produce a composition which is phthalate-free.

Accordingly, there is a need for a soft denture liner, which can provide sufficient comfort for the user and improve adhesion to the gums, while easing the process for separating the liner from the denture at the time the liner is replaced. Moreover, there is a need for a phthalate-free denture liner. Such needs are obtainable by providing denture liner compositions that have a hydrophobic component and a hydrophilic component that is shape-retaining and self-supporting.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a denture liner having both an improved adhesive action to form stronger and more lasting bonds between the denture and the oral cavity and an improved separability from the denture.

It is another object of the present invention to provide an improved denture liner, which can be readily applied and removed.

It is another object of the present invention to provide a denture liner which adjusts denture alignment to conform to user's gums in order to ensure an optimal fit.

It is another object of the present invention to provide a denture liner which is sufficiently soft to conform to the shape of the denture and the shape of the gum.

It is another object of the present invention to provide a denture liner that is self-supporting.

It is another object of the present invention to provide a denture liner that is shape-retaining in the presence of moisture from the mouth.

It is another object of the present invention to provide a denture liner which is sufficiently resilient and durable.

It is another object of the present invention to provide a denture liner composition characterized as plastically deformable.

It is another object of the present invention to provide a denture liner composition capable of being extruded thermoplastically.

It is another object of the present invention to provide a denture liner which minimizes chemical and mechanical bond formation between the denture liner composition and the denture, such that the denture liner can be easily removed from the denture once applied.

It is another object of the present invention to provide a denture liner composition characterized as comprising a mucoadhesive.

It is another object of the present invention to provide a denture liner that controls the rate of hydration of the denture liner.

It is an object of the present invention to provide a denture liner which is phthalate-free.

It is an object of the present invention to reduce the possibility of a denture user from ingesting phthalates.

These and other objectives of the present invention are met by a denture liner for fitting a denture to gums in a mouth having a self-supporting and shape-retaining layer that comprises a volume of a hydrophobic polymer component that inhibits the liner from absorbing moisture and a volume of a hydrophilic polymer component that hydrates a surface of the liner when exposed to moisture. Such liner characteristics provide soft denture liner compositions, which provide sufficient comfort for the user and improved adhesion to the gums, while easing the process for separating the liner from the denture at the time the liner is replaced.

It is an aspect of the invention for a surface of the denture liner that contacts the denture base to provide adhesion to a dry denture base.

It is an aspect of the invention for the denture liner the hydrophobic polymer component and the hydrophilic polymer component are uniformly blended within the denture liner.

It is yet another aspect of the invention for the denture liner to comprise at least two regions each comprising different phases, with the volume of the hydrophilic polymer component is primarily disposed in one phase of the denture liner. In such an embodiment the hydrophilic polymer component can be disposed in all regions of the denture liner.

It is a further aspect of the invention for the hydrophobic component to control the rate of hydration of the denture liner while the denture liner is applied to the gums.

It is still a further aspect of the invention for the denture liner to consist essentially of a single layer.

It is another aspect of the invention for the denture liner to be in the form of a flat sheet.

In one preferred embodiment the hydrophobic polymer component comprises a hydrophobic polymer constituent such as an esterified copolymer of methyl vinyl ether and maleic anhydride, vinyl acetates, acrylate ester derivatives, polybutene, silicone, paraffin wax, and combinations there of. Such vinyl acetates include polyvinyl acetate and ethylene vinyl acetate. Such acrylate ester derivatives include polyethyl methacrylate, polymethyl methacrylate, and combinations thereof. Most preferably the polymer constituent comprises two constituents polyethyl methacrylate and polyvinyl acetate.

In one preferred embodiment the hydrophilic polymer component comprises a hydrophilic polymer constituent such as lower alkyl vinyl ether maleic anhydride copolymers and their monovalent or multivalent salts, natural gums, synthetic polymer derivatives, cellulose derivatives, and combinations thereof. Such natural gums include karaya gum, guar gum, gelatin, algin, alginate, tragacanth, and chitosan. Such synthetic polymer derivatives include polyethylene glycol, polyethylene oxide, acrylamide polymers, polyacrylic acid, polyvinyl alcohol, polyamine, polybutene, silicone, and polyvinylpyrrolidone. Such cellulose derivatives include sodium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, and hydroxyethyl cellulose. In another preferred embodiment the hydrophilic polymer constituent comprises a mixture of natural gums and synthetic polymeric derivatives. In yet another preferred embodiment the hydrophilic polymer constituent comprises a mixture of polyethylene oxide and a cellulose derivative. Most preferably the hydrophilic polymer constituent comprises a mixture of sodium carboxymethylcellulose and polyethylene oxide.

It is yet another aspect of the invention for the denture liner to comprise a plasticizer component comprising at least one plasticizer constituent capable of plasticizing the denture liner. In one preferred embodiment the plasticizer constituent is phthalic acid derivative, glycerol triacetate, citric acid derivative, phosphoric acid derivative, vegetable oil, ester of vegetable oil, glycol derivative, paraffin wax, pentaerythritol fatty acid ester, stearic acid derivative, glycerol monostearate, polyethylene glycol, butyl phthalyl butyl glycolate, and combinations thereof. Such phthalic acid derivatives include butyl phthalyl butyl glycolate, dimethyl phthalate, dibutyl phthalate, and combinations thereof. Moreover, the glycerol triacetate may be triacetin. Suitable citric acid derivatives include triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, and combinations thereof. Moreover, the phosphoric acid derivative may be triphenyl phosphate. Preferably the glycol derivative is diethylene glycol. Preferably the ester of vegetable oils includes caprylic triglyceride, capric triglyceride, propylene glycol di-caprylate/caprate, and combinations thereof. In one embodiment, the plasticizer is preferably glyceryl triacetate.

It is still another aspect of the invention for the denture liner to comprise ethanol when the initial denture liner components are mixed together. Such a component is preferably utilized with denture liner kits that comprise a first compartment with a solid phase composition and a second compartment with a liquid phase composition. The solid phase composition and the liquid composition independently comprise at least one of: a hydrophobic polymer component comprising at least one thermoplastically extrudable hydrophobic polymer; a plasticizer component comprising at least one plasticizer constituent capable of plasticizing the polymer; and an adhesive component comprising at least one hydrophilic adhesive agent.

It is yet another aspect of the invention for the denture liner to comprise a filler component. The filler component inhibits the plasticizer from leaching out of the denture liner and helps denture liner maintain a soft and moldable form. Such filler components include calcium carbonate, silicone dioxide, and combinations thereof.

In some preferred embodiments the denture liners have a hydrophobic polymer component which comprises of from about 15% to about 65% by weight of the total weight of the denture liner composition. Preferably the hydrophobic polymer component is between about 40% to about 65% by weight of the total weight of the denture liner composition. Optionally, the hydrophobic polymer component may be between about 15% to about 35% by weight of the total weight of the denture liner composition.

In some preferred embodiments the hydrophilic polymer component of the denture liner comprises of from about 0.5% to about 45% by weight of the total weight of the denture liner composition. Preferably, the adhesive component of the denture liner comprises of from about 20% to about 40% by weight of the total weight of the denture liner composition. Most preferably the adhesive component comprises about 30% to about 40% by weight of the denture liner.

In some preferred embodiments the denture liners have a plasticizer component comprising of from about 1% to about 55% by weight of the total weight of the denture liner composition. Preferably, the plasticizer component may comprise of from about 10% to about 30% by weight of the total weight of the denture liner composition. Most preferably, the plasticizer component comprises about 16% to about 20% by weight of the denture liner.

Preferably the denture liner mix originally comprises ethanol which comprises of from about 1% to about 10% by weight of the initial denture liner components.

Optionally, the denture liner comprises a filler component which comprises of from about 0.5% to about 10% by weight of the denture liner composition and wherein the filler component is selected from a group consisting of calcium carbonate, silicon dioxide and the like.

A preferred denture liner embodiment comprises a self-supporting and shape-retaining layer that comprises a volume of a hydrophobic polymer component, preferably from about 40% to about 65% by weight of the layer, that inhibits the liner from absorbing moisture and enables the denture liner to maintain its integrity. The layer further comprises a volume of a hydrophilic polymer component, preferably from about 30% to about 40% by weight of the layer, that hydrates a surface of the liner when exposed to moisture. The layer still further comprises a volume of a plasticizer component, preferably from about 16% to about 20% by weight of the layer, that plasticizes the denture liner and enables a surface of the liner to adhere to the denture base when dry. The layer also comprises a volume of a filler component, preferably from about 1% to about 10% by weight of the layer, that inhibits the plasticizer from leaching out of the denture liner.

In some preferred embodiments of the present invention uses all of the same ingredients, excipients, and/or constituents as listed herein except that the embodiments are devoid of phthalate. Accordingly it is best characterized as phthalate-free. Such compositions are suitable for use with the kits and methods as described herein.

As used herein the term “glass transition temperature” means the temperature at which the amorphous domains of a polymer take on the characteristic properties of the glass state-brittleness, stiffness, and rigidity. The term further means the temperature at which cured resins undergo a change from a glassy state to a softer more rubbery state. Moreover the term refers to, among other things, the approximate midpoint of the temperature range over which the glass transition takes place.

As used herein the term “ambient temperature” means the temperature of a medium surrounding an object. The term further refers to the temperature, usually of the air, that surrounds the denture liner. The term further relates to the temperature of a medium, such as gas or liquid, which comes into contact with or surrounds an apparatus such as a denture liner. Ambient temperature is normally defined as the nominal temperature of the air (or other gases, liquids, etc.) that surrounds the component, module, assembly, or system. The term includes but is not limited to room temperature as 23° C.±2° C. (73.4° F.±3.6° F.).

As used herein the term “thermoplastically extrudable polymer” refers to polymers which are capable of softening or fusing when heated and of hardening again when cooled which may further be shaped using a die. Such polymers may further be shaped by forcing through a mold.

As used herein the term “phthalate” means any phthalate including phthalate diesters. The term also refers to phthalic acid derivatives such as dimethyl phthalate, dibutyl phthalate, and butyl phthalyl butyl glycolate. The term also refers to branched alcohol phthalates such as dipropyl phthalate (DPP), diisobutyl phthalate (DIBP), diisohexyl phthalate (DIHP), diisoheptyl phthalate (DIHP), di(2-ethylhexyl) phthalate(DEHP/DOP), diisooctyl phthalate (DIOP), diisononyl phthalate (DINP), diisodecyl phthalate(DIDP), dipropylheptyl phthalate (DPHP), diundecyl phthalate (DUP), diisoundecyl phthalate (DIUP), and ditridecyl phthalate (DTDP/DITP). The term also refers to any mixed alcohol phthalates such as butylbenzyl phthalate (BBP), seven-nine phthalate (79P), nine-eleven phthalate (911P). The term also refers to any linear alcohol phthalate such as dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), six-ten phthalate (610P), eight-ten phthalate (810P), ten-twelve phthalate (1012P).

As used herein the term “phthalate-free” means that the composition does not contain any phthalate including phthalate diesters and other phthalate derivatives.

As used herein the term “percentage by weight” or “weight %” or “% weight”, or “wt. %” means percentage by weight of a given material of the total weight of a mixture or composition.

As used herein the term “volume” means an amount of a given material of a mixture or composition and can be in the form of “percentage by weight” or “weight %” or “% weight”, or “wt. %.”

As used herein the term “contacting” means the act of touching together, which includes, but is not limited to mixing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an embodiment of a denture liner sheet in accordance with the present invention.

FIG. 2 is a cross-sectional view of another embodiment of a denture liner sheet in accordance with the present invention.

FIG. 3 is a cross-sectional view of yet another embodiment of a denture liner sheet in accordance with the present invention.

FIG. 4 is a cross-sectional view of yet another embodiment of a denture liner sheet in accordance with the present invention.

FIG. 5 is a top plan view of the denture liner kit in accordance with the present invention.

FIG. 6 is a cross-sectional view of the denture liner kit of FIG. 1, taken along line A-A.

FIG. 7 is a front plan view of the denture liner kit in accordance with the present invention.

FIG. 8 is a front plan view of various components of the denture liner kit in accordance with the present invention.

FIG. 9 is a front plan view of the denture liner kit in a single container in accordance with the present invention.

FIG. 10 is a side plan view of a mixing tray suitable for use with denture liner kit of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A denture liner according to the present invention has many different functions. It can, for example, serve as a cushion for the denture and provide comfort to the denture wearer. It can fill in the gaps formed by receding gums, so that the denture wearer does not have to get the dentures adjusted every time the shape of the gums changes. It also can act as a denture adhesive without the use of additional adhesive layers. Importantly, the denture liner of the present invention can be much more easily separated from denture than the conventional denture liners. Therefore, the denture wearer can avoid both purchasing additional denture adhesives and getting the dentures adjusted by the dentist by using a denture liner according to the present invention. Such results are obtainable by providing a denture liner with a self-supporting and shape-retaining layer that comprises a volume of a hydrophobic polymer component that inhibits the liner from absorbing moisture and a volume of a hydrophilic polymer component that hydrates a surface of the liner when exposed to moisture. Such results are also obtainable by providing a denture liner that comprises a volume of a hydrophobic polymer component that inhibits the liner from deforming and a volume of a hydrophilic polymer component that hydrates a surface of the liner when exposed to moisture. The denture liner can further be characterized by having a glass transition temperature lower than the lower of an ambient temperature at which the liner is applied and a temperature inside the oral cavity. Preferably the glass transition temperature for these compositions range between −55° C. to 26° C. More preferably, the glass transition temperature is in the range of −55° C. to 0° C. Most preferably, the glass transition temperature is between −55° C. to −70° C.

The denture liner of the present invention includes a polymer component comprising at least one thermoplastically extrudable hydrophobic polymer. In order to provide the liner with mucoadhesive characteristics and to allow the liner to be removed from the denture, the liner includes at least one hydrophilic polymer, which is capable of adhering to the oral cavity such as an area of the gums. This adhesive agent makes the liner less hydrophobic, which weakens the bond between the polymer in the liner and the polymer of the denture. The hydrophilic polymer can be characterized as a class of polymers that are water soluble and the hydrophobic polymer can be characterized as a class of polymers that are as water in-soluble. It is beneficial if the denture liner includes a plasticizer component that is compatible with the hydrophic polymer component. The plasticizer component can be used to enhance the plasticity of the denture liner to improve its moldability.

The denture liner of the present invention, when extruded thermoplastically, cures and sets. The liner is sufficiently soft and moldable such that the liner effectively conforms to the shape of the denture and the shape of the gum. Due to the liner's cohesive rubber-like and flexible state, the hydrophobic component fills in gaps enhancing the seal. Further, the action of saliva activates the adhesive components to produce a viscous gel that further enforces the bond between the denture and gums.

FIGS. 1-4 depict different embodiments of the present invention. FIG. 1 depicts a cross-section of a denture liner 100 in the form of a sheet with an upper surface 110, a lower surface 120, and a liner body 130 disposed between the surfaces. Denture liner 100 comprises homogeneous mixture of a hydrophobic component 101 and a hydrophilic component 102. Denture liner 100 can further comprise a plasticizer that is mixed with the hydrophobic component 101.

When used, the lower surface 120 is applied to a denture base, i.e. the portion of the denture fitted for application to gums in a mouth. The denture liner 100 can be molded and pressed onto the denture base so that the denture liner conforms to the shape and topography of the base and yet maintain the overall integrity of liner 100. Upon application of liner 100 to the base, the denture and liner are inserted into the oral cavity. The upper surface 110 of liner 100 is applied to the gums. The hydrophilic polymers 102 at upper surface 110 swell and form a gel in the presence of moisture on the gums and enable the liner 100 and consequently the denture to adhere to the oral cavity. The hydrophobic polymers 101 inhibit moisture from diffusing through the liner body 130, enabling the denture liner to maintain its integrity and preventing the liner from oozing. Stated another way, the hydrophobic polymers 101 inhibit the hydrophilic polymers 102 from dissolving in the presence of moisture. Over time, moisture may progressively diffuse through the liner body 130. However, the hydrophobic polymers 101 enable the liner to maintain its overall shape and integrity.

The use of a plasticizer enhances the ability of the denture liner to be flexible and moldable. The plasticizer can also be used to provide the surfaces of the denture liner with a tacky quality. The tack provides adhesion of the lower surface 120 to the denture base without requiring moisture from the mouth to hydrate lower surface 120, i.e. the surface of the denture base can be dry.

FIG. 2 depicts a cross-section of a denture liner 200 similar to the denture liner 100 of FIG. 1. Denture liner 200 is also in the form of a sheet with an upper surface 210, a lower surface 220, and a liner body 230 disposed between the surfaces. However, denture liner 200 comprises an in-homogeneous mixture of a hydrophobic component 101 and a hydrophilic component 102. FIG. 2 shows that denture liner 200 comprises two regions in the liner body 230 each comprising a different phase. The first phase 232 is formed in the portion of body 230 towards upper surface 210. The second phase 234 is formed in the portion of body 230 toward lower surface 220. The first phase 232 is characterized by the fact that the volume of the hydrophilic polymer component 202 is primarily disposed in the first phase, i.e. the amount of hydrophilic polymer 202 in the first phase is greater than the amount of hydrophilic polymer 202 in the second phase.

FIGS. 3 and 4 also depict cross-sections of denture liners 300 and 400 similar to the denture liner 100 of FIG. 1. These denture liners 300 and 400 are characterized as comprising adhesive layers 340 and 440 respectively. Adhesive layer 340 is applied to lower surface 320 and comprises a denture adhesive constituent that improves that ability of liner 300 to adhere to the denture base. Suitable denture base constituents include polybutenes, silicones, rubbers, petrolatum, and mixtures thereof. Adhesive layer 440 is applied to upper surface 410 and comprises a mucoadhesive constituent that the promotes the adhesion of the liner to the gums. Suitable mucoadhesive constituents can be well known pastes and powders, including polymers associated with the hydrophilic component. Layers 340 and 400 can be applied as a thin layer to liner bodies 330 and 430 respectively so as not to alter the overall inventive characteristics and function of the denture liner. Layer 340 should be of a limited thickness such that limited bonding occurs between the liner and the denture base. Layer 430 should be of a limited thickness such that the mucoadhesive constituents does not substantially ooze off of the denture liner when applied to the gums, i.e. remains disposed between the liner base 430 and the gums.

Hydrophobic Polymer Component

The denture liner of the present invention can comprise one or more hydrophobic polymers, which can serve as a hydrophobic vehicle, film former, filler between gums and denture, and/or adhesive carrier. Any polymer constituent, which satisfies at least one of these characteristics and which can be extruded with a plasticizer and an adhesive agent to form a denture liner, as required by the present invention, can be used. Examples of polymer constituents that may be used in the present invention include hydrophobic polymers such as polyvinyl acetate (PVA), polybutenes, silicones, paraffin wax, esterified copolymer of methyl vinyl ether and maleic anhydride, hydrophobic acrylate ester derivatives, such as polyethy methacrylate (PEMA) and polymethyl methacrylate (PMMA), organosoluble cellulose, etc. Preferred polymers include esterified copolymer of methyl vinyl ether and maleic anhydride, PEMA, and PVA. In a preferred embodiment the denture liner comprises a mixture of PEMA and PVA.

Preferably the denture liner comprises a greater relative amount of PVA than PEMA. PVA when plasticized exhibits a gummy, tacky consistency. PVA is also considered readily flowable due to its linear and non-rigid polymer backbone. The stoichiometry of the acetate group side chain is not enough to provide yield stress. PEMA, one the other hand, has a longer side chain (1 extra carbon), i.e. the ethyl ester, making its stoichiometry semi-rigid. Thus, PEMA polymers are more resistant to deformation due to the fact that the side chains inhibit the ability of polymers to slide past one another. A hydrophobic polymer component that is a mixture of PEMA and PVA is further characterized by the fact that these polymers are not reactive in each others presence. As a result, the interaction between these hydrophobic polymer constituents is primarily mechanical. The addition of PEMA to PVA enables the denture liner to be self-supporting and maintain its integrity when stress is applied. However, the presence of PVA provides the denture liner with moldability and gap filling qualities that are advantageous for the denture liner. Overall, the combination of the polymers is such that just enough flow is provided to permit the denture liner to creep and fill in the gaps between the denture and gums effectively.

For the denture adhesive kit, however, it is preferable to combine PEMA and PVA because PVA can provide the denture liner with more flexibility, flow and reversibility, which can allow the liner to be more easily removed from the kit and spread onto the denture. This combination surprisingly shows improved tacking qualities.

Another suitable polymer constituent for use with the present invention is esterified copolymer of methyl vinyl ether and maleic anhydride. Such copolymer is available from a commercial supplier. For example, the ISP Corporation of Wayne, N.J. provides polymeric free acid form, anhydride form, mixed salt form, and half ester forms of lower alkyl vinyl ether maleic anhydride polymer under its “GANTREZ” trademark. The “GANTREZ ES Series” which relates specifically to monoethyl ester of poly[methyl vinyl ether/maleic acid] is particularly suitable for the present invention for it provides improved tacking ability of the liner to the denture over the state-of-the-art denture liners. The “GANTREZ ES Series” provides suitable polymer component of the present invention in the half ester form which is produced by opening up the anhydride in alcohol. The commercial supplier offers a range of copolymers with different alkyl chain lengths and molecular weights. Typically, the copolymers are supplied as 50% alcoholic solutions.

Preferably, 100% esterified copolymer of methyl vinyl ether and maleic anhydride is used as a polymer component. One of ordinary skill in the art would readily be able to obtain 100% esterified copolymer of methyl vinyl ether and maleic anhydride by reacting one part of anhydride (available from the supplier) with 2 parts alcohol. Suitable alcohols include methanol, ethanol, propanol, etc. Furthermore, diols, triols and related substances may also be used to make 100% esterified copolymer of methyl vinyl ether and maleic anhydride, however, use thereof is less preferred since the chances of achieving crosslinking with a neighboring copolymer increases.

In general, the hydrophobic polymer content of the denture liner composition may be of from about 15% to about 65% by weight of the denture liner composition, preferably from about 40% to about 65% by weight. Optionally, the hydrophobic polymer content of the denture liner composition may be of from about 15% to about 35% by weight.

Hydrophilic Polymer Component

The present invention may comprise at least one hydrophilic polymer component, which is capable of adhering to the oral cavity. Like the plasticizer, the adhesive agents used in the denture liner should be food grade or better. In addition to mucoadhesive properties, the adhesive agents can also act as, for example, a tackifier and/or a swelling agent.

Since the polymer and the plasticizer are both generally hydrophobic and difficult to remove from the denture surface during cleaning, the adhesive agent provides the liner with some hydrophilic characteristics, weakening the bond between the polymer in the liner and the polymer in the denture. Thus, the liner can be more easily separated from the denture by, for example, applying moisture.

Suitable adhesive constituents include water-soluble polymers having the property of bonding to the oral cavity upon exposure to moisture. Such adhesive materials should be food grade or better and include natural gums and synthetic polymeric derivatives, adhesive materials commonly employed in denture adhesives. Examples of such materials include natural gums such as karaya gum, guar gum, gelatin, alginic acid and its salts, tragacanth, and chitosan, and synthetic polymer derivatives such as polyethylene glycol, acrylamide polymers, polyacrylic acid, polyvinyl alcohol, ethylene oxide polymers, polyvinylpyrrolidone, cellulose derivatives, such as sodium carboxymethylcellulose (NaCMC), hydroxypropyl methylcellulose (HPMC), hydroxyethyl methylcellulose (H EMC), hydroxypropyl cellulose (H PC) and hydroxyethyl cellulose (HEC) and other synthetic gums or polymers. Preferred adhesive agents are NaCMC, polyethylene oxide (polyox) and mixtures thereof.

Unlike, PVA and PEMA, polyox and NaCMC interact by hydrogen bonding to each other in the presence of water/saliva. Polyox is very linear and lubricious polymer chain. Flow and tack of polyox is high when hydrated. NaCMC is rigid, no flow, and has excellent gelling properties when hydrated. A symbiotic interaction can be achieved when polyox and NaCMC are combined in appropriate amounts. NaCMC holds the adhesive-tack properties of polyox in place, preventing the polyox from flowing or diffusing away, and aids in the hydration of the polyox. NaCMC's rigid nature also improves the shear of the hydrophilic component.

In general, the adhesive agent content of the denture liner may be of from about 0.5% to about 45% by weight, preferably from about 20% to about 40% by weight, and most preferably about 30% to about 40% by weight.

Plasticizer Component

Any plasticizer constituent compatible with a hydrophobic polymer in the hydrophobic polymer component may be used. It is preferable that the resulting denture liner has a glass transition temperature that is lower than the lesser of the ambient temperature at which the liner is applied and the temperature inside the oral cavity of the denture wearer. It is preferable that the plasticizer is food grade or better. As with the polymer, two or more plasticizers can be included in the denture liner.

Examples of useful plasticizers constituents in the context of the present invention include phthalic acid derivatives, such as BPBG, dimethyl phthalate, dibutyl phthalate, etc., glycerol triacetate (triacetin), citric acid derivatives, such as triethyl citrate, etc., phosphoric acid derivatives, such as triphenyl phosphate, etc., glycol and glycol derivatives, such as diethylene glycol, triethylene glycol ester of fatty acids, etc., paraffin waxes, pentaerythritol esters of fatty acids, stearic acids derivatives, glycerol monostearate, polyethylene glycols, etc. The derivatives of these compounds include various esters. Most preferably vegetable oil including ester of vegetable oil selected from the group consisting of caprylic triglyceride, capric triglyceride, propylene glycol di-caprylate/caprate, and combinations thereof.

In some embodiments, triacetin and BPBG are preferred plasticizers. BPBG has a boiling point from about 210° C. to about 220° C. (5 mmHg) (C₄H₄COOC₄H₄COCH₂COOC₄H₉). Triacetin has a boiling point of 285° C. These plasticizers allow the liner to set with the passage of time, depending on the temperature and the amount of moisture in the mouth.

In general, the plasticizer content of the denture liner may be of from about 1% to about 55% by weight of the denture liner composition, preferably about 10% to about 30% by weight, most preferably about 16 to about 20% by weight.

In phthalate-free embodiments, vegetable oils, and esters thereof such as caprylic triglyceride, capric triglyceride, propylene glycol di-caprylate/caprate, and combinations of these are preferable. Although not wishing to be bound by this disclosure, it is believed that the vegetable oils avoid stearic hindrance that may occur when large molecules are untangling, providing a denture liner with improved tacking and softening qualities.

Additional Ingredients

The denture liner according to the present invention can contain additional ingredients. These ingredients can improve the functionality of the liner and/or provide ancillary benefits to the denture wearer.

The denture liner can include a filler component. The filler component inhibits the plasticizer from leaching out of the denture liner and helps the denture liner maintain a soft and moldable form. Suitable filler components include calcium carbonate, silicon dioxide and the like. In general, the filler component of the denture liner may be of from about 0.5% to about 10% by weight of the denture liner, preferably about 6.0% by weight.

Ethyl alcohol can be added to the denture liner in order to improve its flowability for shaping and application of the denture liner, particularly in the denture liner kit as will be described below. Since the alcohol will quickly evaporate at the time when the denture is applied, the negative effects generally associated with its use in dental products are minimized and the denture liner can set and function unhampered by alcohols extra softening effects. The amount of the alcohol present in the denture liner composition is generally of from about 1% to about 10 weight % of the initial denture liner components.

Other suitable additional ingredients include therapeutically active agents suitable for treating individuals in need thereof. These agents include antimicrobial agents, such as iodine, sulfonamides, bisbiguanides, or phenolics, antibiotics such as tetracycline, neomycin, kanamycin, metronidazole, or clindamycin, anti-inflammatory agents, such as aspirin, acetaminophen, naproxen and its salts, ibuprofen, ketorolac, flurbiprofen, indomethacin, eugenol, or hydrocortisone, dental desensitizing agents, such as potassium nitrate, strontium chloride or sodium fluoride, anesthetic agents, such as lidocaine or benzocaine; anti-fungals, aromatics, such as camphor, eucalyptus oil, and aldehyde derivatives, such as benzaldehyde; insulin, steroids, and anti-neoplastics. Certain forms of therapy and combinations of these agents in the same delivery system may be useful in order to obtain an optimal effect.

Still other suitable additional ingredients include colorants and preservatives, such as methyl and propyl parabens. The denture liner compositions of the present invention may also include one or more components, which provide flavor, flagrance, and/or sensation benefit. These components include natural or artificial sweetening agents, menthol, menthyl lactate, wintergreen oil, peppermint oil, spearmint oil, leaf alcohol, as well as coolants 3-1-menthoxypropane-1,2-diol and paramenthane carboxyamide agents, such as N-ethyl-p-menthane-3-carboxamide.

Phthalate-Free

One preferred embodiment of the present invention uses all of the same ingredients, excipients, and/or constituents as listed above except that it is devoid of any phthalate. Accordingly it is best characterized as phthalate-free. Although applicant does not wish to be bound by this disclosure, it is believed at least by consumer advocacy groups that phthalates, which are typically added to many plasticizer components, may be detrimental to the health of humans and animals. Hence in order to promote a safer denture liner, as well as the marketing of products devoid of phthalate, it is desirable to make a denture liner which is phthalate-free.

Accordingly, phthalate-free embodiments comprise a hydrophobic polymer component having at least one polymer constituent; a plasticizer component having at least one plasticizer constituent capable of plasticizing the polymer component; and an adhesive component comprising at least one hydrophilic adhesive agent. Preferably, these embodiments have a glass transition temperature that is lower than the lower of an ambient temperature at which the liner is applied and a temperature inside an oral cavity. Optionally, the polymer constituent is a thermoplastically extrudable polymer. The hydrophobic polymer constituent may may be selected from the group consisting of polyvinyl acetate, acrylate esters, organosoluble cellulose, polybutene, silicone, paraffin wax, and combinations of these. The acrylate ester derivative is selected from the group consisting of polyethyl methacrylate, polymethyl methacrylate, and combinations of these. Preferably, the polymer constituent is a combination of polyethyl methacrylate and polyvinyl acetate. Esterified copolymer of methyl vinyl ether and maleic anhydride is also a suitable polymer.

The phthalate-free embodiments use a plasticizer constituent selected from the group consisting of glycerol triacetate, citric acid derivatives, phosphoric acid derivatives, vegetable oil esters, glycol derivatives, paraffin wax, pentaerythritol fatty acid ester, stearic acid derivatives, glycerol monostearate, polyethylene glycol, and combinations thereof. One of ordinary skill in the art may use any plasticizer with these embodiments so long as the plasticizer is devoid of phthalic acid derivatives including those selected from the group consisting of butyl phthalyl butyl glycolate, dimethyl phthalate, dibutyl phthalate, and combinations thereof. Examples of suitable plasticizers include triacetin, triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, triphenyl phosphate, diethylene glycol, caprylic triglyceride, capric triglyceride, propylene glycol di-caprylate/caprate, and combinations of these.

The phthalate-free embodiments may use any adhesive component that one of ordinary skill in the art would use to make a denture liner so long as it is devoid of phthalate. Suitable adhesive components include natural gum derivatives such as karaya gum, guar gum, gelatin, algin, alginate, tragacanth, chitosan, and synthetic polymer derivatives such as polyethylene glycol, acrylamide polymers, polyacrylic acid, polyvinyl alcohol, polyamines, polyethylene oxide, polyvinylpyrrolidone, lower alkyl vinyl ether maleic anhydride copolymers and their monovalent or multivalent salts and combinations thereof. Adhesive agents also include ingredients selected from the group consisting of sodium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, and combinations thereof. Preferably, the adhesive agent includes sodium carboxymethylcellulose, and polyethylene oxide.

PREFERRED EMBODIMENT

In a preferred embodiment of the present invention a denture liner is formed comprising a self-supporting and shape-retaining layer that comprises a volume of a hydrophobic polymer component, preferably from about 40% to about 65% by weight of the layer, that inhibits the liner from absorbing moisture and enables the denture liner to maintain its integrity. The layer further comprises a volume of a hydrophilic polymer component, preferably from about 30% to about 40% by weight of the layer, that hydrates a surface of the liner when exposed to moisture. The layer still further comprises a volume of a plasticizer component, preferably from about 16% to about 20% by weight of the layer, that plasticizes the denture liner and enables a surface of the liner to adhere to the denture base when dry. The layer also comprises a volume of a filler component, preferably from about 1% to about 10% by weight of the layer, that inhibits the plasticizer from leaching out of the denture liner and helps the denture liner maintain a soft and moldable form.

It is preferable that the hydrophobic polymer component comprises two hydrophobic polymer constituents. One hydrophobic polymer constituent can be flowable enabling the denture liner to be deformed and molded. The other hydrophobic polymer constituent can be a semi-rigid polymer such that denture liner remains self-supporting and is able to maintain its integrity once applied. As such, the preferred hydrophobic polymer constituents are PEMA, preferably from about 1% to about 5% by weight of the layer, and PVA, preferably from about 40% to about 60% by weight of the layer.

It is preferable that the hydrophilic polymer component comprises two hydrophilic polymer constituents. The two hydrophilic polymer constituents can interact with one another such that the constituents when hydrated are retained at the surface of the denture liner. As such, the preferred hydrophilic constituents are polyox, preferably from about 15% to about 25% by weight of the layer, and NaCMC, preferably from about 5% to about 15% by weight of the layer.

It is preferable that the plasticizer component is Triacetin.

It is preferable that the filler component comprises a filler constituent that is a calcium carbonate.

Process for Producing Denture Liner

The denture liner in accordance with the present invention can be manufactured by combining and mixing liquid and solid components. The mixtures may then be thermoplastically extruded to form a film, which is then cut to form individual liners.

Specifically, thermoplastic extrusion can be carried out using various methods. The extruder can be a melt pump. The mixed, polymeric material is melted, and then the melted material is forced via the die into a sheet form.

Also, the extruded liner can be prepared using an injection molding method. In this method, all the components of the denture liner are blended together at room temperature (about 15° C. to 35° C.). The blended compositions are then poured into the twin screw extruder hopper chamber. The chamber is set at about 80° C. to about 100° C. The co-rotating screws further blend the mixtures at an increased temperature and pressure. The heated and blended mixtures may then be injection molded into a die, which is pre-shaped into the desired form of the liner.

Other techniques, such as casting, calendaring, coating and extrusion, or a combination of two or more of these techniques, could also be used. In addition, in one embodiment, the components of the denture liner are first mechanically softened by a ring roller, smoothed on a hydraulic press, and die-cut as desired into denture liner shapes or other desired shapes.

The extruded liners can be of from about 0.1 mm to about 1 mm thick, preferably from about 0.25 mm to about 0.5 mm. If the liner is thicker than about 1 mm, the denture wearer may experience discomfort. If, however, the denture liner is thinner than about 0.1 mm, both the adhesive and the lining properties of the denture liner may be negatively affected.

Once the denture liner is formed, a denture adhesive layer and/or a mucoadhesive layer can optionally be coated on to the surfaces of the liner using techniques readily known to those skilled in the art.

Denture Liner Kit

While, as discussed above, the denture liner according to the present invention can be thermoplastically extruded to form a sheet, which is then cut and packed for use, the denture liner according to the present invention can also be produced in a form of a kit. The kit preferably comprises a packet, which contains two compartments, each of which houses denture liner ingredients in different phases.

The ingredients in one of the compartments can be, for example, in the solid phase, while the ingredients in the other compartment can be in the liquid phase. These compartments are separated by a separator, which can be removed or breached in order to combine and mix all of the denture liner ingredients. Once the ingredients are combined inside the packet, the packet it ruptured and the contents applied to the denture. It is preferable to thoroughly mix ingredients before placing them on the denture.

An exemplary kit in accordance with the present invention is shown in FIGS. 5 and 6. This kit is in the form of a packet 501, which is similar to a ketchup packet or the like commonly available on the market. However, packet 501 contains at least a first compartment 502 and a second compartment 503 divided by a separator 504. As shown in FIG. 6, first compartment 502 contains solid phase powder components 505 and second compartment 503 contains liquid phase component 506. Separator 504 may be breached by squeezing one of the compartments, thus propelling its contents into the other compartment.

Solid (e.g., powder) components in accordance with the present invention can include the polymer component and the adhesive. The liquid component can include the plasticizers. However, it should be noted that there is no specific limitations as to which ingredient may be present in liquid or solid form in the kit. For example, some polymers, which are a part of the polymer component, may also be present in liquid form.

It is preferable that the denture liner components placed in the kit be in such proportions that the resulting mixture is sufficiently flowable to be spread on the denture. This can be achieved, for example, by including an additional amount of plasticizer or including alcohol in the composition. The addition of alcohol, which is placed in the compartment containing liquid ingredients, can provide the denture liner composition with flowability, ultimately evaporating to leave behind a denture liner, which has the desired properties.

FIG. 7 shows denture liner kit 510 in accordance with the present invention. Kit 510 comprises first compartment 512 containing a predetermined amount of solid phase composition 514. Also shown is second compartment 516 containing a predetermined amount of liquid phase composition 518. First compartment 512 and second compartment 516 may be made out of any material known to one of ordinary skill in the art which is capable of containing a powder or a liquid, such as glass or preferably plastic. Also, first compartment 512 and second compartment 516 may further contain a cover (not shown in FIG. 6) for containing the solid and liquid phase compositions within the compartment. Aluminum foil is a suitable cover for the compartments for it facilitates use by being easily removable.

Referring now to FIG. 8, various components of the denture liner kit in accordance with the present invention are shown. The various components may be optionally included with the kit to facilitate users on forming and shaping their denture liner. For example, cutting implement 520 is provided in order to help a user cut the resulting polymer composition to a particular shape. Cutting implement 520 may be a pair of scissors, razor blade, or the like. Stir rod 522 is provided to facilitate users in mixing the liquid composition and solid composition to uniformity. Stir rod 522 may be made out of any suitable material for mixing a powder and a liquid including but not limited to glass, plastic, or wood. Dropper 524 is also provided in order to help a user mix liquid composition with solid composition. Emery board 526 is provided to help a user contour the liner to a desired shape. Bottle 528 is shown as an alternative shape for second compartment, for any small plastic or glass bottle is suitable for holding liquid component.

FIG. 9 shows a single container 530 where first compartment 512 and second compartment 516 are combined in one single container. Divider 532 is a wall between first compartment 512 and second compartment 516. Divider 532 may be made out of an easily breakable material such as plastic or tin foil. When a user breaks the divider, the components of first compartment 512 and second compartment 516 mix together in a single container.

The components of the present invention can also be easily mixed by supplying mixing tray such as shown in FIG. 10. User simply places the solid composition and liquid composition onto the tray 534 and mixes the components to a uniform composition.

The following are some non-limiting examples of denture liners in accordance with the present invention.

EXAMPLE 1

A denture liner was prepared by combining components in amount as listed in Table 1. This liner was made by blending all the components in a Hobart7 mixer. A pre weighed sample, was sandwiched between two release papers. Using a hydraulic Carver7 press, and a shim gap of 0.5 mm, the sample was compressed at 10 tons for 20 seconds at 210 deg. F. The compressed composition was then cut by hand to the shape of the denture liner. TABLE 1 Ingredient Content (wt. %) PEMA 21 Triacetin 28 BPBG (Morflex 190) 21 Polyox 15 NaCMC 15

The polymer component of this denture liner is PEMA, which functions as a main film former, vehicle, gap filler and adhesive carrier. The plasticizer component consists of triacetin and BPBG. The adhesive component includes polyox and NaCMC. Specifically, polyox is a tackifier and a mucoadhesive. NaCMC is a swelling component and a mucoadhesive.

The denture liner of this example cures and sets as a result of the action of the plasticizers. This makes the denture fit to the gums, so that the action of saliva creates a bond. The adhesives strengthen this bond.

Since this denture liner includes PEMA, the liner can easily adhere to the denture and prevent the denture from sliding off the liner. The presence of the two adhesive agents, which are the only hydrophilic components of this denture liner, allows the denture liner to be easily separated from the denture after use. Furthermore, the mucoadhesive properties of these adhesive agents allow the liner to more securely place the denture onto the gums without the need for an additional denture adhesive.

This denture liner can also be produced by first combining triacetin and BPBG, which are both in liquid form. Then, the PEMA, NaCMC and polyox powders are added to the liquid, and the resulting composition is thoroughly mixed to form a slurry. Once a slurry containing all components is prepared, it is thermoplastically extruded to form a thin film, which is then cut into individual pieces.

EXAMPLE 2

A denture liner is prepared by combining components in amounts as listed in Table 2 in the same manner as the liner in Example 1. TABLE 2 Ingredient Content (wt. %) PEMA 35 Triacetin 17.5 BPBG (Morflex 190) 17.5 Polyox 15 NaCMC 15

This denture liner also contains a trace level of ethyl alcohol, which is added to make the material more flowable. The other components of this denture liner perform the same functions as in the liner of Example 1.

EXAMPLE 3

A denture liner kit is prepared by providing a packet with two compartments, as shown in FIG. 1. PEMA, NaCMC and polyox are placed in compartment 1 in powder form. PVA, triacetin and BPBG, which are in liquid form, are placed in compartment 2. The amounts of each of the ingredients in the kit are as listed in Table 3. TABLE 3 Ingredient Content (wt. %) Phase Triacetin 28 Liquid BPBG 21 Liquid PVA 5 Solid PEMA 16 Solid Polyox 15 Solid NaCMC 15 Solid

Once the separator 3 between compartment 1 and compartment 2 is breached, the components are mixed to form a denture liner composition. In this composition, each of the components performs the same functions as in the liner of Example 1. PVA, like PEMA, is used as a vehicle polymer, which adds flexibility, flow and reversibility to the denture liner.

EXAMPLE 4

An in vivo test was conducted to compare the holding and comfort ability of the denture liner of the composition of Example 1, as recited in Table 1. Human volunteers who had previously used dental adhesive creams were asked to compare this denture liner to the conventional Sea-Bond7 dental adhesive laminate in accordance with U.S. Pat. No. 4,632,080, which utilizes an adhesive combination of polyox and CMC, by using both products individually to secure dentures in their mouths. Some volunteers were given the denture liner in accordance with the present invention, while others were given the Sea Bond 7 denture adhesive. Each volunteer was asked to rate the hold of the denture on the scale from 1 to 10 (10 being the best) immediately after application and at 30 minutes after application, as well as at 1, 3 and 6 hours after application. The cumulative/average results of the comparative study are presented in Table 4. TABLE 4 Time Denture Liner Sea-Bond 7 Initial Assessment 7.6 8.0 30 min. 9.0 8.1  1 hr. 9.4 7.8  4 hr. 9.0 5.4  6 hr. 9.1 5.2

As demonstrated in Table 4, the denture liner of the invention provides significantly improved bonding over time over the conventional denture adhesive, which utilizes at least the same adhesive components. This result was surprising in that the denture liner of the present invention was not expected to provide a better hold than the conventional denture adhesive. It is believed that the improved hold is the result of the synergy between the setting power of the hydrophilic components of the liner and the adhesive power of the hydrophilic adhesive component.

EXAMPLE 5

A denture liner kit is prepared by providing a packet with two compartments, as shown in FIG. 1. PEMA, NaCMC, polyox, and 100% esterfied Gantrez® are placed in compartment 1 in powder form. PVA, triacetin and vegetable oils, which are in liquid form, are placed in compartment 2. The amounts of each of the ingredients in the kit are as listed in Table 5. TABLE 5 Ingredient Content (wt. %) Phase Triacetin 28 Liquid Vegetable Oil 21 Liquid PVA 5 Solid PEMA 16 Solid Polyox 15 Solid NaCMC 10 Solid esterified copolymer of 5 Solid methyl vinyl ether and maleic anhydride

Table 5 shows an additional example of various embodiments of the present invention which are phthalate-free. Another similar example uses all of the same ingredients listed in Table 5 except the esterified copolymer of methyl vinyl ether and maleic anhydride is absent and an additional 5% NaCMC is added in its place.

EXAMPLE 6

A denture liner is prepared by combining components in amounts as listed in Table 6 in the same manner as the liner in Example 1. TABLE 6 Ingredient Content (wt. %) Triacetin 11.0 Polyethylmethacrylate 1.0 Polyethylene oxide 20.0 Cellulose gum 4.0 Polyvinyl Acetate 57.9 Calcium carbonate 6.0 Red 27 Lake 0.1 Total 100.0

This denture liner includes the filler component Calcium carbonate. The other components perform the same functions as described for the liners of Examples 1-5.

The denture liners have a glass transition temperature that is most preferably lower than the lower of an ambient temperature at which the liner is applied and a temperature inside an oral cavity (i.e. approximately 98.6 degrees F. (37 degrees C.)).

The glass transition temperature of a sample having the ingredients of Example 1 was measured using a DSC (differential scanning calorimetry). The glass transition temperature was found to be 63° C. A similar sample having PEMA, Triacetin, and BPBG was measured and the glass transition temperature of the material was found to be 70° C. The optimum and preferred Tg range for products of the present invention is between −55° C. to −70° C. However, workable results are obtainable for compositions having a Tg between −55° C. to 26° C.

While the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. 

1. A denture liner for fitting a denture to gums in a mouth, comprising: a self-supporting and shape-retaining layer in the form of a sheet that comprises a first surface that is applied to a denture base and a second surface that is applied to the gums, that maintains it shape and integrity when the denture base and liner are applied to the gums, and that is from about 0.1 mm to about 1 mm thick; the layer further comprising: a volume of a hydrophobic polymer component from about 15% to about 65% by weight of the layer that inhibits the liner from absorbing moisture; a volume of a hydrophilic polymer component from about 0.5% to about 45% by weight of the layer that hydrates a surface of the liner when exposed to moisture; and a volume of a plasticizer component from about 1% to about 55% by weight of the layer that plasticizes the denture liner and enables a surface of the liner to adhere to the denture base when dry; wherein the hydrophobic component controls the rate of hydration of the denture liner while the denture liner is applied to the gums.
 2. The denture liner of claim 1, wherein the denture liner consists essentially of the layer.
 3. The denture liner according to claim 1, wherein the hydrophobic polymer component comprises a hydrophobic constituent selected from the group consisting of: esterified copolymer of methyl vinyl ether and maleic anhydride; vinyl acetates such as polyvinyl acetate and ethylene vinyl acetate; acrylate ester derivatives such as polyethyl methacrylate, polymethyl methacrylate, and organosoluble cellulose; polybutene; silicone; paraffin wax; and combinations thereof.
 4. The denture liner according to claim 1, wherein the hydrophilic component comprises a hydrophilic constituent selected from the group consisting of: natural gums such as karaya gum, guar gum, gelatin, algin, alginate, tragacanth, and chitosan; synthetic polymer derivatives such as polyethylene glycol, polyethylene oxide, acrylamide polymers, polyacrylic acid, polyvinyl alcohol, polyamine, polybutene, silicone, and polyvinylpyrrolidone; cellulose derivatives such as sodium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, and hydroxyethyl cellulose; lower alkyl vinyl ether maleic anhydride copolymers and their monovalent or multivalent salts; and combinations thereof.
 5. The denture liner of claim 1, further comprising a plasticizer component comprising at least one plasticizer constituent capable of plasticizing the denture liner.
 6. The denture liner according to claim 5, wherein the plasticizer constituent is selected from the group consisting of phthalic acid derivative, glycerol triacetate, citric acid derivative, phosphoric acid derivative, vegetable oil, ester of vegetable oil, glycol derivative, paraffin wax, pentaerythritol fatty acid ester, stearic acid derivative, glycerol monostearate, polyethylene glycol, butyl phthalyl butyl glycolate, and combinations thereof.
 7. The denture liner according to claim 1, further comprising ethanol when initial denture liner components are mixed together.
 8. The denture liner according to claim 1, further comprising a filler component.
 9. The denture liner according to claim 8, wherein the filler component is selected from a group consisting of calcium carbonate, silicone dioxide, and combinations thereof.
 10. The denture liner according to claim 8, wherein the filler component is from about 1% to about 10% by weight of the layer.
 11. The denture liner according to claim 1, wherein the hydrophobic polymer component is from about 40% to about 65% by weight of the layer.
 12. The denture liner according to claim 1, wherein the hydrophilic polymer component is from about 30% to about 40% by weight of the layer.
 13. The denture liner according to claim 1, wherein the plasticizer component is from about 16% to about 20% by weight of the layer.
 14. A denture liner for fitting a denture to gums in a mouth, comprising: a self-supporting and shape-retaining layer that comprises a volume of a hydrophobic polymer component that inhibits the liner from absorbing moisture and a volume of a hydrophilic polymer component that hydrates a surface of the liner when exposed to moisture.
 15. The denture liner of claim 14, wherein the layer is in the form of a sheet that comprises a first surface that is applied to a denture base and a second surface that is applied to the gums.
 16. The denture liner of claim 14, wherein the layer is from about 0.1 mm to about 1 mm thick;
 17. The denture liner according to claim 15, wherein the denture liner maintains it shape and integrity when the denture base and liner are applied to the gums.
 18. The denture liner of claim 15, wherein the first surface provides adhesion to the denture base.
 19. The denture liner of claim 18, wherein the first surface provides adhesion to the denture base when dry.
 20. The denture liner of claim 15, wherein the denture liner further comprises a first phase and a second phase, the first surface forming a portion of the first phase and the second surface forming a portion of the second phase, and the volume of the hydrophilic polymer component is primarily disposed in the second phase.
 21. The denture liner of claim 15, wherein the hydrophobic polymer component and the hydrophilic polymer component are uniformly blended within the denture liner.
 22. The denture liner of claim 15, wherein the application of the first surface of the denture liner to the base inhibits the first surface of the denture liner from being exposed to moisture.
 23. The denture liner of claim 15, wherein the application of the second surface of the denture liner to the gums hydrates the second surface.
 24. The denture liner of claim 23, wherein the hydrophobic component controls the rate of hydration of the denture liner while the denture liner is applied to the gums.
 25. The denture liner of claim 14, wherein the denture liner consists essentially of the layer.
 26. The denture liner according to claim 14, wherein the hydrophobic polymer component comprises a hydrophobic constituent selected from the group consisting of: esterified copolymer of methyl vinyl ether and maleic anhydride; vinyl acetates such as polyvinyl acetate and ethylene vinyl acetate; acrylate ester derivatives such as polyethyl methacrylate, polymethyl methacrylate, and organosoluble cellulose; polybutene; silicone; paraffin wax; and combinations thereof.
 27. The denture liner according to claim 14, wherein the hydrophobic polymer component is from about 15% to about 65% by weight of the layer.
 28. The denture liner according to claim 27, wherein the hydrophobic polymer component is from about 40% to about 65% by weight of the layer.
 29. The denture liner according to claim 14, wherein the hydrophilic component comprises a hydrophilic constituent selected from the group consisting of: natural gums such as karaya gum, guar gum, gelatin, algin, alginate, tragacanth, and chitosan; synthetic polymer derivatives such as polyethylene glycol, polyethylene oxide, acrylamide polymers, polyacrylic acid, polyvinyl alcohol, polyamine, polybutene, silicone, and polyvinylpyrrolidone; cellulose derivatives such as sodium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, and hydroxyethyl cellulose; lower alkyl vinyl ether maleic anhydride copolymers and their monovalent or multivalent salts; and combinations thereof.
 30. The denture liner according to claim 14, wherein the hydrophilic polymer component is from about 0.5% to about 45% by weight of the layer.
 31. The denture liner according to claim 30, wherein the hydrophilic polymer component is from about 30% to about 40% by weight of the layer.
 32. The denture liner of claim 14, further comprising a plasticizer component comprising at least one plasticizer constituent capable of plasticizing the denture liner.
 33. The denture liner according to claim 32, wherein the plasticizer constituent is selected from the group consisting of phthalic acid derivative, glycerol triacetate, citric acid derivative, phosphoric acid derivative, vegetable oil, ester of vegetable oil, glycol derivative, paraffin wax, pentaerythritol fatty acid ester, stearic acid derivative, glycerol monostearate, polyethylene glycol, butyl phthalyl butyl glycolate, and combinations thereof.
 34. The denture liner according to claim 14, wherein the plasticizer component is from about 1% to about 55% by weight of the layer.
 35. The denture liner according to claim 34, wherein the plasticizer component is from about 16% to about 20% by weight of the layer.
 36. The denture liner according to claim 14, further comprising ethanol when initial denture liner components are mixed together.
 37. The denture liner according to claim 36, wherein the ethanol is from about 1% to about 10% by weight of the initial denture liner components.
 38. The denture liner according to claim 14, further comprising a filler component.
 39. The denture liner according to claim 38, wherein the filler component is selected from a group consisting of calcium carbonate, silicone dioxide, and combinations thereof.
 40. The denture liner according to claim 38, wherein the filler component is from about 1% to about 10% by weight of the layer.
 41. A denture liner, consisting essentially of: a layer that comprises at least a volume of a hydrophobic polymer component that inhibits the liner from absorbing moisture and a volume of a hydrophilic polymer component that hydrates a surface of the liner when exposed to moisture.
 42. The denture liner according to claim 41, wherein the hydrophobic polymer component comprises a hydrophobic constituent selected from the group consisting of: esterified copolymer of methyl vinyl ether and maleic anhydride; vinyl acetates such as polyvinyl acetate and ethylene vinyl acetate; acrylate ester derivatives such as polyethyl methacrylate, polymethyl methacrylate, and organosoluble cellulose; polybutene; silicone; paraffin wax; and combinations thereof.
 43. The denture liner according to claim 41, wherein the hydrophilic component comprises a hydrophilic constituent selected from the group consisting of: natural gums such as karaya gum, guar gum, gelatin, algin, alginate, tragacanth, and chitosan; synthetic polymer derivatives such as polyethylene glycol, polyethylene oxide, acrylamide polymers, polyacrylic acid, polyvinyl alcohol, polyamine, polybutene, silicone, and polyvinylpyrrolidone; cellulose derivatives such as sodium carboxymethylcellulose, hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, and hydroxyethyl cellulose; lower alkyl vinyl ether maleic anhydride copolymers and their monovalent or multivalent salts; and combinations thereof.
 44. The denture liner according to claim 41, further comprising a filler component.
 45. The denture liner according to claim 44, wherein the filler component is selected from a group consisting of calcium carbonate, silicone dioxide, and combinations thereof.
 46. The denture liner of claim 41, further comprising a plasticizer component comprising at least one plasticizer constituent capable of plasticizing the denture liner.
 47. The denture liner according to claim 46, wherein the plasticizer constituent is selected from the group consisting of phthalic acid derivative, glycerol triacetate, citric acid derivative, phosphoric acid derivative, vegetable oil, ester of vegetable oil, glycol derivative, paraffin wax, pentaerythritol fatty acid ester, stearic acid derivative, glycerol monostearate, polyethylene glycol, butyl phthalyl butyl glycolate, and combinations thereof. 